When the Stryker Rejuvenate and ABGII were recalled in July of 2012,
citing potential risk of fretting and corrosion at the neck juncture, many of
the implants had already been removed during revision surgeries. Unfortunately,
since most physicians were unaware of the problems with the implants, the
operative reports were unlikely to list this corrosion. In other words, since
the doctors hadn’t been told what issues to look for, there were few records
stating that corrosion was a factor in the revision surgery. When Stryker
originally told hospitals and surgeons (in an Urgent Field Safety Report in
April of 2012) that there could be corrosion or fretting and release of metal
ions, there was still no mention of that corrosion occurring anywhere except at
the neck juncture.
Therefore, the neck juncture would likely have been the only place
physicians would have examined when taking out the implant. In the same vein,
when implant recipients came to their doctor complaining of pain or other
symptoms, the doctor would have ordered x-rays, an MRI and a bone scan. Again,
without clear information regarding what to look for, many physicians might
have attributed their patient’s complaints to external issues such as the aging
process. The Rejuvenate, unlike former
metal-on-metal hip implants, is a four-part device with a ceramic ball and a
plastic liner in the cup. Because of these improvements, it was believed there
would be no metal parts rubbing against one another causing metal ion shear.
Unfortunately, the company may have not considered the potential of the
small metal “trundles,” located on either end of the neck piece, as a risk for
metal ion release. These trundles allow the neck piece to slip inside of them
then the trundles on the neck pop into the stem on one end and into the ball on
the other. Body fluids can become trapped inside these trundles, causing
corrosion and leading to metal ions being released into the surrounding tissues
or into the bloodstream. While the level of metal in the body would not reach
the same levels as with the all-metal implant, there is no good amount of metal
to have in the body. Elevated levels of cobalt and chromium can lead to:
·
Chronic pain
·
Infection
·
Failure of the hip implant
·
Necrosis (tissue death)
·
Pseudo tumors
·
Metal toxicity
So long as physicians are not informed about the potential risks of hip
implants, they will be unaware of what they need to look for and may even have
dismissed patient complaints or misdiagnosed patient concerns. More information
is crucial so that patients are informed of the risks of hip implants and surgeons
are apprised of the potential risk of the implants.
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